High Definition Multimedia Interface (HDMI®) is a digital audio/visual connector interface capable of transmitting uncompressed and compressed streams, and can provide an interface between any compatible digital audio/video (A/V) source device, herein also referred to as a module, such as a set-top box (STB) or set-back box (SBB), a DVD player, a PC, a video game system, an A/V receiver, and a compatible digital audio and/or video monitor device, such as a television (TV) or a digital television (DTV). HDMI solves the problem of “too many cables” in A/V systems. Audio, visual, status and control information may be transmitted via one cable in the system
Consumer Electronic Control (CEC) is a protocol used to control devices that are attached using HDMI. HDMI, such as HDMI 1.2a released in December 2005, supports CEC features, command sets, and CEC compliance tests. CEC features, as may be defined from time to time in the CEC Specification, include routing control, standby, system information, and feature abort. Other, optional features may include one touch recording, deck control, tuner control, On Screen Display (OSD) display, OSD name transfer, device menu control, RC pass-through, power status and vendor-specific commands. Of course, it is understood that the HDMI specification continues to be enhanced and enlarged and new CEC commands are expected to be added as developed.
Using a single cable, CEC control allows a user to control all HDMI devices with a remote control or commander user interface, including powering on or off connected devices and generally commands initiated by devices to other devices. It thus solves the problem of “too many remote controls or commanders.” Consider an example of “one-touch play.” A user can press play on one HDMI device, such as a DVD, and operation of CEC commands causes the A/V receiver to automatically turn on and switch to the correct input, which automatically turns on the TV; this in turn automatically switches to the correct input received from the A/V receiver.
In spite of these advantages, the HDMI CEC signal path from device to device is unacceptably slow. The bandwidth associated with the HDMI CEC specification is very low and the delay associated with data transfer rate is long, with the transfer rate, including ECC buffered memory and checksum, approximately 52 bytes per second. This standard CEC signal path of the HDMI connector is half duplex and slow, resulting in a sluggish remote control or commander user interface experienced by a user.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.